Mitosis and Meiosis

Mitosis and Meiosis are two ways that cells reproduce. By mitosis a cell splits to create two identical copies of the original cell. In meiosis cells split to form new cells with half the usual number of chromosomes, to produce the ability for sexual reproduction.

The activities of mitosis and meiosis are similar in that they each create chromosomes, but in mitosis the created cell has the 46 chromosomes, whereas in meiosis the two created cells combine to create a cell with the 46 chromosomes.

From a human prospective, nature had some real obstacles to overcome, and has overcome some of it with creative engineering with the human body. Mitosis describes the process by which the nucleus of one cells divides to create two new nuclei. Each of the nuclei contains an identical copy of the DNA. Each created cell will contain the 46 chromosomes necessary. Just about the entire DNA duplicated in the human body is done through mitosis. Chromosomes begin to condense and in doing so begin to take on the form that they are depicted from. Each of the chromosomes at that time are two identical chromosomes, each copy is called a chromatid.

The system of reproduction made the move from being asexual to sexual reproduction possible. The parent cells divide and allow two parent cells to combine to create offspring, or sexual reproduction. These parent cells incorporate genetic information from both parents but retain only half the amount of DNA. With only half the amount of DNA retained, when the two cells combine the produce the proper amount of 46 DNA chromosomes are maintained. This systematic process is meiosis. Meiosis is the process by which sex cells are created. If you are a male, the body uses meiosis to create sperm cells and if you are female, the body uses meiosis to create egg cells. Other cells in the body contain 46 chromosomes: 23 come from the father and 23 come from the mother. In meiosis, 23 chromosomes come from the father and 23 come from the mother. When the egg and the sperm cells unite you have to 46 necessary chromosomes.

For a great example of mitosis, imagine a person scraping an elbow or knee. In addition to being uncomfortable, some skin is lost. The body then begins to take a skin cell and duplicates it to produce identical matches of skin cells to heal the scrap. The dividing and reproducing of healthy replacement cells is mitosis.

Human beings cannot just divide in two and make another duplicate human, which would be like cloning. Some starfish can do this. They can break off an arm and grow an identical starfish. This process is an example of asexual reproduction where offspring are produced genetically identical to the parent. In contrast, sexual reproduction is needed to produce human life. In sexual reproduction, sex cells from two parents combine in the process of fertilization, leading to the formation of a new genetically distinct individual. This is the process of meiosis.

All living things, including human beings, are made up of cells. How these cells divide through mitosis and meiosis, determines how the cell cycle is controlled and how the reproduced cell is incorporated to produce life.

A: Cells split to form new cells with half the usual number of chromosomes
B: Cells split to identical cells
C: Cells inherit genetic codes from other cells
D: Cells genetically clone themselves

A: Cells split to create two identical copies of the original cell
B: Cells split to create new cells that are different
C: Cells inherit genetic codes
D: Cells reproduce at three times the number of chromosomes.

A: Genes
B: Traits
C: Cells
D: Tissues

A: A human being giving birth
B: A tree growing leaves
C: A lawn growing weeds
D: A starfish breaking an arm and reproducing from it

A: 46
B: 48
C: 54
D: 60

A: Twice the amount
B: Half the amount
C: Four times the mount
D: Equal to the amount

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